1. Field of the Invention
The present invention relates generally to roofing materials and, more particularly, to a grid for use in retaining shingles on a roof.
2. Discussion of the Prior Art
A conventional roof construction includes roof sheeting material, such as plywood, which is nailed to the rafters defining a roof. A layer of waterproof material, such as an asphalt impregnated felt material, is applied over the sheeting, and is covered by shingles which are applied in horizontal courses from the bottom edge of the roof up, with each course overlapping the one beneath.
A common type of shingle used in this roof construction is known as a strip shingle, and includes a strip of asphaltic or fiberglass impregnated material having, for example, a length of three feet, a width of twelve inches, and a thickness of between one-eighth to one-half inches. Slits are provided along one edge of the strip and extend inward laterally to provide an impression that a plurality of shingles are included in each strip. In addition, an aggregate material is applied over one face of the strip to texture the surface and to provide a desired appearance. The material used in strip shingles typically possesses a degree of flexibility such that the shingles may be bent, rolled or otherwise worked, if necessary.
Attempts have been made to simplify installation of shingles on a roof by guiding alignment of the shingles or by presenting fastening expedients for holding the shingles in place once positioned. However, such conventional attempts have either fallen short of obtaining both of these goals, or require the use of specially-made shingles, increasing the cost of the system.